This invention relates to electrical connectors for coupling high-density electrical circuits and more particularly to a compressive connector element for establishing electrical connections between dense circuitries on adjacent printed circuit cards or circuit boards.
Nowadays, highly integrated semiconductor modules are mounted on cards which may be plugged into circuit boards. High-density connector leads are provided for coupling the modules to other devices on the same or on other boards. Separate entities of high computing and memory capacity are created by interconnecting cards or boards, each comprising at least one semiconductor module. Such interconnection of adjacent cards or circuit boards, comprising highly integrated semiconductor modules and associated dense connector leads, is even more critical than off-card connections where card circuitry can be connected to input/output cabling on a rigid frame.
Generally speaking, the requirements for card-to-card or board-to-board connectors, connecting semiconductor circuitries in adjacent modules, are the following:
(a) the distance covered by the contact should be as short as possible; PA1 (b) positive mechanical retention of contact elements should be provided; PA1 (c) the connector elements should be held in position under positive spring action; and PA1 (d) high rigidity and stiffness of the clamping member should provide for equal and uniform spring action.
U.S. Pat. No. 4,057,311 issued to Evans discloses an electrical board-to-board connector for coupling semiconductor module circuits on two spaced-apart cards. According to the teaching of this reference, two boards to be connected are mounted in different planes with edges overlapping. The connector body has multiple parallel connection elements sandwiched between the overlapping edges of the two adjacent boards. This approach requires connector leads to be placed on oppositely directed surfaces of the boards.
U.S. Pat. No, 3,597,660 issued to Jensen, et al discloses an off-card connector for coupling high-density edge conductors on module circuit boards with input-output circuit conductors of a cabling network. The overlays are formed on a flexible thin layer of polyimide material by printed circuit techniques and contact pressure is achieved through a resilient body under a pressure applying mechanism.
A major problem associated with connecting electrical circuits on separate circuit boards and providing an electrical connection therebetween, especially during the assembly process, is the potential for attracting dust or other contaminants to the connectors. It is important that the electrical connection be of high quality, due to the relatively small dimensions of the electrical lines. The integrity of the electrical connections is a function of the amount of extraneous material that adheres to the conductive elements. Accordingly, the copper surfaces to be connected should be as clean as possible prior to and during the assembly process.
It would be advantageous to provide a system for electrically and structurally connecting circuits on separate printed circuit boards.
It would further be advantageous for this system of circuit connections to be simply constructed with a minimum of moving parts and assembly complexity.
Moreover, it would be advantageous to provide a system for electrically connecting circuits on separate boards while ensuring the highest degree of cleanliness prior to and during the final assembly.
It would also be advantageous to provide an electrical bond between separate circuits on respective circuit boards having a means for positive mechanical retention so that the possibility of eventual disconnection is minimized or eliminated.
It would further be advantageous to provide a system for connecting a plurality of separate conductors on abutting circuit boards such that positive retention is assured equally for all of the connected conductors.
It would also be advantageous to provide preformed elements that are deformable under pressure to provide wiping and cleaning action of the copper surfaces immediately prior to completing the electrical connections.